Aqueous zinc-ion batteries (AZIBs) are promising for large-scale energy storage due to their high theoretical capacity and safety. However, dendrite formation and side reactions at the Zn/electrolyte interface limit their practical applications. This study introduces urea as an environmentally friendly and low-cost additive to the electrolyte of AZIBs to improve Zn deposition and suppress side reactions. Urea adsorbs onto the Zn surface, forming a blocking layer that prevents water from contacting the metal, thereby reducing side reactions. It also regulates Zn²+ flux distribution, enabling uniform and rapid Zn²+ transport for homogeneous deposition. With urea, a Zn/Zn symmetric cell demonstrated long-term cycling stability (over 2100 h) at high current density (5 mA·cm⁻²) and capacity (5 mAh·cm⁻²). The Zn/NH₄V₄O₁₀ full cell with urea exhibited excellent cycling performance and an average Coulombic efficiency of 99.98%. These results indicate that urea is an effective and low-cost additive strategy for achieving highly reversible AZIBs. The study highlights the importance of interfacial engineering in improving AZIB performance, particularly under high-test conditions. The experimental methods included material preparation, electrolyte preparation, cathode fabrication, and characterization techniques such as zeta potential, contact angle, SEM, and XRD. Electrochemical measurements were conducted to evaluate the performance of the cells. The findings demonstrate that urea can significantly enhance the reversibility and stability of AZIBs, making them more viable for practical applications.Aqueous zinc-ion batteries (AZIBs) are promising for large-scale energy storage due to their high theoretical capacity and safety. However, dendrite formation and side reactions at the Zn/electrolyte interface limit their practical applications. This study introduces urea as an environmentally friendly and low-cost additive to the electrolyte of AZIBs to improve Zn deposition and suppress side reactions. Urea adsorbs onto the Zn surface, forming a blocking layer that prevents water from contacting the metal, thereby reducing side reactions. It also regulates Zn²+ flux distribution, enabling uniform and rapid Zn²+ transport for homogeneous deposition. With urea, a Zn/Zn symmetric cell demonstrated long-term cycling stability (over 2100 h) at high current density (5 mA·cm⁻²) and capacity (5 mAh·cm⁻²). The Zn/NH₄V₄O₁₀ full cell with urea exhibited excellent cycling performance and an average Coulombic efficiency of 99.98%. These results indicate that urea is an effective and low-cost additive strategy for achieving highly reversible AZIBs. The study highlights the importance of interfacial engineering in improving AZIB performance, particularly under high-test conditions. The experimental methods included material preparation, electrolyte preparation, cathode fabrication, and characterization techniques such as zeta potential, contact angle, SEM, and XRD. Electrochemical measurements were conducted to evaluate the performance of the cells. The findings demonstrate that urea can significantly enhance the reversibility and stability of AZIBs, making them more viable for practical applications.